This invention relates to the field of power lawn mowers, and particularly to rotary lawn mowers having provision for bagging the mown grass. Mowers of this sort have a carefully designed housing in which the wind generated by the rapidly rotating blade is directed to carry with it the mown grass, the housing including a "wind tunnel" terminating a discharge passage through which the mown grass is delivered to the bag.
There are occasions where it is desirable to operate such a mower without bagging the mown grass: an example is the use of the mower in mulching operations, where the mown grass is to remain in the area of the cutter blade until it is reduced to suitably small dimensions for depositing directly on the lawn. For these and other purposes a door or closure is provided near the discharge opening, to obstruct the air flow passage and to retain turbulent air movement within the housing: a collecting bag is at this time totally unnecessary.
When a bag is used, its mouth must be properly positioned with respect to the discharge passage when the latter is open. Aerodynamic factors related to the power available from the engine, the speed of the blade, and the porosity of the bag determine the maximum size of the discharge passage for adequate bagging to occur without "dribbling" or deposit of some cuttings on the mown lawn. Experience has taught that a bag mouth of this size is not sufficiently large to enable the bag to be emptied conventionally therethrough, and one expedient to alleviate this is to have a bag with a large second opening to dump cuttings through, together with some means for closing the second opening thereafter.
Of course the bag must be removed from the mower for emptying, and it is desireable for safety reasons to be sure that the mower is not operated in its bagging mode unless the bag is properly installed.